The long term goal of this proposal is to develop a model system for vaccines that will induce protective immunity. It is based on the idea that the cytokine profiles of CD4+ helper T cells determine the form of the immune response that develops, and takes advantage of a new understanding of how cytokine synthesis is regulated in CD4+ T cells. Central to this project is the use of antigenic constructs (cytokine fusion proteins) in which antigens are covalently linked to cytokine molecules in order to direct the form of the immune response in an antigen-specific manner. Cytokine fusion proteins will be constructed to contain the antigen ovalbumin (OVA) fused to GM-CSF, IL-12, IFN-gamma, IL-2 or IL-4. Established molecular techniques will be used to produce the cytokine chimeric proteins. OVA, a soluble single chain protein which is relatively easy to manipulate and study, will be fused to cytokines which have a significant influence on CD4+ T cell and B cell differentiation. These cytokine-OVA fusion proteins will be injected, without adjuvants, into strains of mice that differ with regard to susceptibility to various pathogens and with regard to cytokine regulation in their T cells. The anti-OVA specific humoral and cellular immune responses, as well as the cytokine profiles of T cells that develop in the immunized mice will be examined. The fusion proteins will be used to induce primary anti-OVA response and to modify established OVA-specific immune responses, Thereby determining which fusion proteins and what doses or what combinations of the proteins will induce the best IgG1, the best Ig2a, the best IgE, and in particular the best CTL and the best DTH OVA-specific responses, in several different strains of mice. These experiments will thus allow us to "customize" the form of immunity induced against OVA and suggest strategies for "customizing" vaccines that will be effective in all strains of mice. The proposed studies will be performed as a collaborative effort among investigators with extensive experience in the construction and evaluation of cytokine fusion proteins, in the investigation of the complex cellular interactions that occur in the regulation of cytokine synthesis, and in the immunotherapy of neoplastic and allergic diseases. The combined complementary expertise of the two laboratories will uniquely enable the investigators to complete the overall objectives of the project. The results with OVA-cytokine fusion proteins will provide the basis for future studies by these investigators with pertinent and/or improved fusion proteins for the treatment of allergic disease, using allergens such as rye grass and dust mite, whose sequences are known, and of neoplastic disease, using tumor specific antigens such as lymphoma idiotype, or the mutant p53 tumor suppressor protein. In these diseases, and appropriate form of immunity in absent, and vaccination with cytokine fusion proteins could induce a protective form of immunity.